<!DOCTYPE html>
<title>CSS Anchor Positioning Test: Effects from @position-try in CSS Typed OM</title>
<link rel="help" href="https://drafts.csswg.org/css-anchor-position-1/#fallback-apply">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  @position-try --pt {
    left: anchor(right);
    top: 50px;
    width: anchor-size(width);
    height: 40px;
  }
  #cb {
    position: relative;
    width: 100px;
    height: 100px;
    border: 1px solid black;
  }
  #anchor {
    position: absolute;
    left: 10px;
    top: 10px;
    width: 20px;
    height: 20px;
    background: coral;
    anchor-name: --a;
  }
  #target {
    position: absolute;
    background: skyblue;
    position-anchor: --a;
    left: 9999px; /* force overflow */
    position-try-fallbacks: --pt;
  }
</style>

<div id=cb>
  <div id=anchor></div>
  <div id=target></div>
</div>
<script>
  function assert_unit_value(actual, expected) {
    assert_true(actual instanceof CSSUnitValue);
    assert_true(expected instanceof CSSUnitValue);
    assert_equals(actual.value, expected.value);
    assert_equals(actual.unit, expected.unit);
  }

  test(() => {
    assert_unit_value(target.computedStyleMap().get('left'), CSS.px(30));
    assert_unit_value(target.computedStyleMap().get('top'), CSS.px(50));
    assert_unit_value(target.computedStyleMap().get('width'), CSS.px(20));
    assert_unit_value(target.computedStyleMap().get('height'), CSS.px(40));
  }, 'Effects of position-try-fallbacks are visible in the computed values');
</script>
